org.opensubsystems.core.www
Class PageElementCacheTag

java.lang.Object
  javax.servlet.jsp.tagext.TagSupport
      javax.servlet.jsp.tagext.BodyTagSupport
          org.opensubsystems.core.www.PageElementCacheTag

All Implemented Interfaces:

java.io.Serializable, javax.servlet.jsp.tagext.BodyTag, javax.servlet.jsp.tagext.IterationTag, javax.servlet.jsp.tagext.JspTag, javax.servlet.jsp.tagext.Tag

Direct Known Subclasses:

BlockElementTag, WebModuleInitTag

public class PageElementCacheTag
extends javax.servlet.jsp.tagext.BodyTagSupport

Custom tag providing ability to cache elements of the page usually from custom tags and then display them at later point when requested. The main purpose is to allow other tags to specify elements, such as css includes or javascript includes at one spot, e.g. using initialization tag. These elements will then be place on a specific places at the page using this tag. It also allows derived tags to cache their content and then other tags to fetch them and display at other places.

Version:

$Id: PageElementCacheTag.java,v 1.10 2007/01/07 06:14:09 bastafidli Exp $

Author:

Miro Halas

See Also:

Serialized Form

Code reviewer:

Miro Halas

Code reviewed:

1.7 2006/04/13 00:21:23 jlegeny

Field Summary

static java.lang.String	CACHE_INDICATOR Indicator to use in attributes to signal to retrieve content from the cache.
static java.lang.String	CSS_ELEMENT CSS style sheets cache.
static java.lang.String	JS_ELEMENT JavaScript js import cache.
protected java.lang.String	m_strCacheas If this id is specified then the content will not be printed into output but instead will be cached under id specified in this attribute.
protected java.lang.String	m_strId Id of the cached element to retrieve.
static java.lang.String	PAGE_ELEMENTS_CACHE Messages collected during processing of current request.
static java.lang.String	SCRIPT_ELEMENT JavaScript script cache.

Fields inherited from class javax.servlet.jsp.tagext.BodyTagSupport

bodyContent

Fields inherited from class javax.servlet.jsp.tagext.TagSupport

id, pageContext

Fields inherited from interface javax.servlet.jsp.tagext.BodyTag

EVAL_BODY_BUFFERED, EVAL_BODY_TAG

Fields inherited from interface javax.servlet.jsp.tagext.IterationTag

EVAL_BODY_AGAIN

Fields inherited from interface javax.servlet.jsp.tagext.Tag

EVAL_BODY_INCLUDE, EVAL_PAGE, SKIP_BODY, SKIP_PAGE

Constructor Summary

PageElementCacheTag()
Constructor for custom tag.

Method Summary

protected void	cache(java.lang.String strPageElementId, java.lang.String strItemToCache) Add item for specific page element to the cache.
int	doEndTag()
int	doStartTag()
java.lang.String	getCacheas()
protected java.lang.String	getCachedContent(java.lang.String strPageElementId) Get the cached content.
protected java.lang.String	getCachedContent(java.lang.String strPageElementId, boolean bRemove) Get the cached content.
protected java.lang.String	getCachedContent(java.lang.String strPageElementId, boolean bRemove, java.lang.String strSeparator) Get the cached content.
protected java.util.List	getCachedContentElements(java.lang.String strPageElementId, boolean bRemove) Get the elements of cached content elements.
java.lang.String	getId()
void	setCacheas(java.lang.String strCacheas)
void	setId(java.lang.String strId)

Methods inherited from class javax.servlet.jsp.tagext.BodyTagSupport

doAfterBody, doInitBody, getBodyContent, getPreviousOut, release, setBodyContent

Methods inherited from class javax.servlet.jsp.tagext.TagSupport

findAncestorWithClass, getParent, getValue, getValues, removeValue, setPageContext, setParent, setValue

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface javax.servlet.jsp.tagext.Tag

getParent, setPageContext, setParent

Field Detail

PAGE_ELEMENTS_CACHE

public static final java.lang.String PAGE_ELEMENTS_CACHE

Messages collected during processing of current request.

See Also:

Constant Field Values

CSS_ELEMENT

public static final java.lang.String CSS_ELEMENT

CSS style sheets cache.

See Also:

Constant Field Values

JS_ELEMENT

public static final java.lang.String JS_ELEMENT

JavaScript js import cache.

See Also:

Constant Field Values

SCRIPT_ELEMENT

public static final java.lang.String SCRIPT_ELEMENT

JavaScript script cache.

See Also:

Constant Field Values

CACHE_INDICATOR

public static final java.lang.String CACHE_INDICATOR

Indicator to use in attributes to signal to retrieve content from the cache.

See Also:

Constant Field Values

m_strId

protected java.lang.String m_strId

Id of the cached element to retrieve.

m_strCacheas

protected java.lang.String m_strCacheas

If this id is specified then the content will not be printed into output but instead will be cached under id specified in this attribute.

Constructor Detail

PageElementCacheTag

public PageElementCacheTag()

Constructor for custom tag.

Method Detail

doStartTag

public int doStartTag()
               throws javax.servlet.jsp.JspException

Specified by:

doStartTag in interface javax.servlet.jsp.tagext.Tag

Overrides:

doStartTag in class javax.servlet.jsp.tagext.BodyTagSupport

Throws:

javax.servlet.jsp.JspException

doEndTag

public int doEndTag()
             throws javax.servlet.jsp.JspException

Specified by:

doEndTag in interface javax.servlet.jsp.tagext.Tag

Overrides:

doEndTag in class javax.servlet.jsp.tagext.BodyTagSupport

Throws:

javax.servlet.jsp.JspException

getId

public java.lang.String getId()

Overrides:

getId in class javax.servlet.jsp.tagext.TagSupport

Returns:

String - Id of the cached element to retrieve.

getCacheas

public java.lang.String getCacheas()

Returns:

String - New Id under which the output will be cached

setId

public void setId(java.lang.String strId)

Overrides:

setId in class javax.servlet.jsp.tagext.TagSupport

Parameters:

strId - - Id of the cached element to retrieve.

setCacheas

public void setCacheas(java.lang.String strCacheas)

Parameters:

strCacheas - - New Id under which the output will be cached

cache

protected void cache(java.lang.String strPageElementId,
                     java.lang.String strItemToCache)

Add item for specific page element to the cache.

Parameters:

strPageElementId - - constant representing HTML page element for which the item will be cached

strItemToCache - - element to cache

getCachedContent

protected java.lang.String getCachedContent(java.lang.String strPageElementId)

Get the cached content.

Parameters:

strPageElementId - - id of the cached element to get

Returns:

String - cached content or empty string if nothing is cached, but never null

getCachedContent

protected java.lang.String getCachedContent(java.lang.String strPageElementId,
                                            boolean bRemove,
                                            java.lang.String strSeparator)

Get the cached content.

Parameters:

strPageElementId - - id of the cached element to get

bRemove - - remove the element from the cache after it is retrieved

strSeparator - - separator for particular cached items

Returns:

String - cached content or empty string if nothing is cached, but never null

getCachedContent

protected java.lang.String getCachedContent(java.lang.String strPageElementId,
                                            boolean bRemove)

Get the cached content.

Parameters:

strPageElementId - - id of the cached element to get

bRemove - - remove the element from the cache after it is retrieved

Returns:

String - cached content or empty string if nothing is cached, but never null

getCachedContentElements

protected java.util.List getCachedContentElements(java.lang.String strPageElementId,
                                                  boolean bRemove)

Get the elements of cached content elements.

Parameters:

strPageElementId - - id of the cached element to get

bRemove - - remove the element from the cache after it is retrieved

Returns:

Lists - cached content or empty List if nothing is cached, but never null